I. Field of the Invention
This invention relates generally to implantable cardiac rhythm management devices, and more particularly relates to a header assembly electrically and mechanically coupled to a pulse generator of the implantable device. The header assembly of the cardiac rhythm management device includes a housing having an electrically interconnected triple port or quadruple port formed in the housing, wherein each port is adapted for receiving a corresponding sensing and/or pacing lead. The electrically interconnected ports reduce the number of required hermetically sealing connections when the conductors of at least two sensing and/or pacing leads are electrically coupled together. Each port of the header assembly has two terminal blocks positioned therein, wherein each terminal block is adapted for coupling a pin and/or ring of the terminal end of each corresponding lead. Feedthrough wires electrically couple the terminal blocks to the electronic circuit of the pulse generator. Jumper wires electrically couple preselected terminal blocks of at least two ports, thereby electrically coupling the corresponding pins and/or rings of at least two leads, ultimately resulting in a simultaneous transmission of an identical signal to the electrically coupled leads.
II. Discussion of the Related Art
Various cardiac rhythm management devices capable of pacing or defibrillating a patient's heart comprise a pulse generator having an electronic circuit and power supply contained within a metal casing, commonly referred to as "the can". A lead, capable of transmitting a therapeutic electrical signal generated by the pulse generator to the heart, is electrically coupled to the electronic circuit of the pulse generator. A "header" having a receptacle or port is commonly provided in order to "plug" the lead into the rhythm management device and electrically couple the lead to the electronic circuit contained within the can. Over the years, the receptacles located in the header of the implantable cardiac rhythm management device and the terminal connector end of a corresponding lead have been standardized by the International Standards Organization (ISO). In the standard connector and receptacle arrangement, an elongated terminal socket or receptacle is formed in the header portion of the rhythm management device and an elongated connector adapted to be received in the receptacle is formed on the terminal end of the lead.
When two leads are required, a separate receptacle is formed in the header for each corresponding lead. Representative examples of such devices having two receptacles appear in U.S. Pat. No. 5,545,188, issued to Bradshaw et al. (hereinafter the '188 device) and U.S. Pat. No. 5,336,246, issued to Dantanarayana (hereinafter the '246 device). The '188 and '246 devices include a metal casing having a header assembly attached thereto. The header comprises two independent receptacles embedded in an insulating epoxy. The header is sealably attached to the can and each receptacle includes insulated contacts and conductive wire coupling the contacts to the electronic circuit contained within the can. Leads of suitable complimentary construction insert into respective receptacles. The first receptacle may be, for example, associated with atrial sensing and pacing and the second receptacle may be, for example, associated with ventricular sensing and pacing.
Currently, such cardiac rhythm management devices may be used, for example, to administer pacing therapy to a Congestive Heart Failure (CHF) patient having a higher degree of AV-block or an AV conduction disorder. The rhythm management device, suited for pacing the ventricle, may be used to administer the desired pacing therapy to the ventricle, synchronous with the intrinsic atrial rate. Such pacing therapy may require a lead associated with the right atrium, a lead associated with the left ventricle, and a lead associated with the right ventricle. In this instance, it is desirable to transmit the same pacing signal through both the left and right ventricular leads. In order to electrically couple the three leads to the two receptacles of the cardiac rhythm management device, it is current practice to interconnect the right and left ventricular leads with an adapter and sleeve. The adapter then plugs into a corresponding receptacle of the cardiac rhythm management device, wherein the pacing through the leads may be unipolar or extended bipolar pacing. Utilizing an adapter and sleeve to interconnect two or more leads increases the required number of sealing connections.
During implantation of a cardiac rhythm management device incorporating such an adapter for the leads, the physician must create a first pocket for the cardiac rhythm management device and a second pocket to hold the adapter and coiled leads. The second pocket is typically created in a separate plane from the pulse generator in order to decrease risk of erosion. The use of an adapter complicates the surgical procedure, increases the length of time in surgery and overall cost of implanting the device, and increases the chance of skin erosion and associated infection.
Hence, there is a need for a header assembly that eliminates the need to use an adapter to interconnect two or more leads without unduly increasing the overall size of the header housing. The present invention addresses these needs.